I recently posted a question but couldn't get any help from it so here goes again:
I am new to Linux. I downloaded Ubuntu 12.10 onto a USB drive to put on an old laptop just for fun. I realized that Ubuntu is awesome and wanted to install it. The install worked fine but here is the problem:

when I boot it from the hard drive I can't get wireless. There are no wireless routers listed, nor is "enable wireless".

When I boot it from the USB drive (i.e. "Try Ubuntu" at the first pop-up) it automatically connects to wireless. A dozen nearby routers show up and "enable wireless" is visible. I cannot just boot from USB every time because it is only 4GB compared to a 500GB hard drive.

I really want to use Ubuntu; it seems great, but I also need wireless service.
Am I using a wrong form of Ubuntu? What is the problem here, and how do I fix it?